In-line monitoring of oled layer thickness and dopant concentration

ABSTRACT

An organic light-emitting diode (OLED) deposition system includes two deposition chambers, a transfer chamber between the two deposition chambers, a metrology system having one or more sensors to perform measurements of the workpiece within the transfer chamber, and a control system to cause the system to form an organic light-emitting diode layer stack on the workpiece. Vacuum is maintained around the workpiece while the workpiece is transferred between the two deposition chambers and while retaining the workpiece within the transfer chamber. The control system is configured to cause the two deposition chambers to deposit two layers of organic material onto the workpiece, and to receive a first plurality of measurements of the workpiece in the transfer chamber from the metrology system.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Application Ser. No.62/964,612, filed on Jan. 22, 2020, the disclosure of which isincorporated by reference.

TECHNICAL FIELD

This disclosure pertains to in-line monitoring of layer thickness anddopant concentration for organic light-emitting diode (OLED) layers.

BACKGROUND

An organic light-emitting diode (OLED or Organic LED), also known as anorganic EL (organic electroluminescent) diode, is a light-emitting diode(LED) that includes a light emissive layer formed of a film of organiccompound that emits light in response to an electric current. Thisorganic layer is situated between two electrodes; typically, at leastone of these electrodes is transparent. OLEDs are used to create digitaldisplays in devices such as television screens, computer monitors,portable systems such as smartwatches, smartphones, handheld gameconsoles, PDAs, and laptops.

OLEDs typically include multiple organic layers, e.g., an electroninjection layer (EIL), an electron transport layer (ETL), a holeblocking layer (HBL), the light emissive layer (EML), an electronblocking layer (EBL), a hole transport layer (HTL) and a hole injectionlayer (HIL). In some fabrication techniques, the multiple organic layersare formed by a sequential deposition process using multiple depositionchambers, where each chamber deposits a particular OLED layer on thesubstrate.

End-of-line metrology systems, in which manufactured substrates aremeasured after a complete run of the substrate through the multipledeposition chambers, have been used to monitor completed substrates toensure that the OLED devices meet specifications. Such end-of-linemethods may utilize optical imaging and/or ellipsometry techniques.

SUMMARY

In one aspect, an organic light-emitting diode (OLED) deposition systemincludes a workpiece transport system configured to position a workpiecewithin the OLED deposition system under vacuum conditions, two or moredeposition chambers, a transfer chamber interconnected to the two ormore deposition chambers, a metrology system having one or more sensorspositioned to perform measurements of the workpiece within the transferchamber, and a control system to control a sequential deposition of therespective layers of organic material onto the workpiece by the two ormore deposition chambers to form an organic light-emitting diode layerstack. Each deposition chamber is configured to deposit respectivelayers of organic material onto the workpiece, and the two or moredeposition chambers are coupled such that vacuum is maintained aroundthe workpiece while the workpiece is transferred between a firstdeposition chamber and a second deposition chamber of the two or moredeposition chambers by the workpiece transport system. The transferchamber is configured to receive the workpiece from the two or moredeposition chambers by the workpiece transport system while maintainingvacuum and retaining the workpiece within the transfer chamber. Thecontrol system is configured to cause the first deposition chamber todeposit a first layer of a first organic material onto the workpiece,cause the workpiece transport system to transfer the workpiece from thefirst deposition chamber to the transfer chamber, receive a firstplurality of measurements of the workpiece in the transfer chamber fromthe metrology system, cause the workpiece transport system to transferthe workpiece from the transfer chamber to the second depositionchamber, and cause the second deposition chamber to deposit a secondlayer of a second organic material onto the first layer on workpiece tobuild at least a portion of the organic light-emitting diode layerstack.

In another aspect, an organic light-emitting diode (OLED) depositionsystem includes a workpiece transport system configured to position aworkpiece within the OLED deposition system under vacuum conditions, twoor more deposition chambers, a transfer chamber interconnected to thetwo or more deposition chambers and configured to receive the workpiecefrom the two or more deposition chambers by the workpiece transportsystem while maintaining vacuum and retaining the workpiece within thetransfer chamber, a metrology system having one or more sensorspositioned to perform measurements of the workpiece within the transferchamber, and a control system to control a sequential deposition of therespective layers of organic material onto the workpiece by the two ormore deposition chambers to form an organic light-emitting diode layerstack. Each deposition chamber is configured to deposit respectivelayers of organic material onto the workpiece, and the two or moredeposition chambers are coupled such that vacuum is maintained aroundthe workpiece while the workpiece is transferred between a firstdeposition chamber and a second deposition chamber of the two or moredeposition chambers by the workpiece transport system. The metrologysystem includes a first light source to generate a first light beam, anda second light source to generate a second light beam to inducephotoluminescence in the layer on the workpiece in the transfer chamber.At least one of the one or more sensors is positioned to receivereflections of the first light beam from the workpiece within thetransfer chamber to perform reflectometry measurements and generate athickness measurement of a layer on the workpiece from the reflectometrymeasurement. At least one of the one or more sensors is positioned toreceive emissions from the layer on the workpiece within the transferchamber to perform photoluminescence measurements of the layer on theworkpiece. The control system is configured to cause the firstdeposition chamber to deposit a first layer of a first organic materialonto the workpiece, cause the workpiece transport system to transfer theworkpiece from the first deposition chamber to the transfer chamber,receive the thickness measurement and the photoluminescence measurementfrom the metrology system, cause the workpiece transport system totransfer the workpiece from the transfer chamber to a second depositionchamber of the two or more deposition chambers, and cause the seconddeposition chamber to deposit a second layer of a second organicmaterial onto the first layer on workpiece to build at least a portionof the organic light-emitting diode layer stack.

In another aspect, a computer program product has instructions to causeone or more data processing apparatuses to cause a first depositionchamber to deposit a first layer of a first organic material onto theworkpiece, cause a workpiece transport system to transfer the workpiecefrom the first deposition chamber to a transfer chamber, receive a firstplurality of measurements of the workpiece in the transfer chamber froma metrology system, cause the workpiece transport system to transfer theworkpiece from the transfer chamber to a second deposition chamber, andcause the second deposition chamber to deposit a second layer of asecond organic material onto the first layer on workpiece to build atleast a portion of the organic light-emitting diode layer stack.

Implementations may include, but are not limited to, one or more of thefollowing possible advantages. Rapid in-line process monitoring andcontrol for OLED doping concentrations and deposition rates can beachieved. The monitoring apparatus is customizable and can be integratedat one or more points in a production line, e.g., within multipletransfer chambers located between a series of deposition tools. Therapid analysis and feedback can fit within established TAKT time(average time between the start of production of one unit and the startof production of the next unit) requirements. Obtaining feedback beforethe end-of-line for OLED deposition characteristics can result inimproved device performance, tighter yields and yield enhancement, andreduced cost of production. Both the combinedreflectometry-photoluminescence method and combined digital holographicmicroscopy-photoluminescence method exhibit high resolution andsensitivity to thin film characteristics, are relatively easier to modelthan other methods, e.g., than ellipsometry, and can be compatible withfiber optics-based implementation for remote sensing, which reduces thefootprint and contamination inside chamber. Due to the fast speed of thereflectometry measurements and a tolerance to focus offset and tiltvariations, impact from vibration of the OLED system is minimized.Additionally, the hardware required to perform these in-linemeasurements are relatively easy to integrate with existing hardwarewhich can result in lower cost of integration. Also, in-linemeasurements can be performed under vacuum condition without filmdeposited on top of the measured sample with least amount of time lapse.As such, material properties measured can be closely representative ofthe deposit chamber condition. It is expected the in-line measurementwill closely correlate to the end-of-line measurement. Both measurementscan be complimentary to one another.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Methods and materials aredescribed herein for use in the present invention; other, suitablemethods and materials known in the art can also be used. The materials,methods, and examples are illustrative only and not intended to belimiting.

Other features and advantages of the invention will be apparent from thefollowing detailed description and figures, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a schematic of an example organic light-emittingdiode (OLED) deposition system including an in-line process monitoringand control system.

FIG. 2A illustrates a schematic of an example transfer chamber includingan in-line process monitoring and control system.

FIG. 2B illustrates a schematic of another example transfer chamberincluding an in-line process monitoring and control system.

FIG. 3A illustrates a schematic of a metrology device array on an axisA-A.

FIG. 3B illustrates a cross-sectional schematic of a metrology devicearray along axis A-A.

FIG. 3C illustrates a two-dimensional array of metrology devices.

FIG. 4 illustrates a schematic of an example workpiece including testregions.

FIG. 5 illustrates a schematic of an example reflectometry andphotoluminescence apparatus for an in-line process monitoring andcontrol system.

FIG. 6 illustrates a schematic of an example digital holographicmicroscopy device and photoluminescence apparatus for an in-line processmonitoring and control system.

FIG. 7 is a flow diagram of an example process of the in-line processmonitoring and control system.

Like reference numbers and designations in the various drawings indicatelike elements.

DETAILED DESCRIPTION

Variations in deposition processes can result in variations in dopantconcentrations and layer thicknesses that result in device performanceissues, e.g., low yield or device-to-device non-uniformity. End-of-linecharacterization techniques can detect issues in the deposition processresulting from one or more or all of the multiple deposition chambers.However, there is a significant lag between a start of a depositionprocess on an OLED production line and a characterization measurement bythe end-of-line metrology of the one or more or all layers that aredeposited, e.g., 15 to 30 minutes of delay. This lag includes both (1)time for the substrate to reach the end of the line, which depends onthe number of layers, and (2) time needed for the measurement itself.Utilizing end-of-line measurements to provide process monitoring canresult in a delay in a feedback loop to the OLED deposition system tobecome aware of any abnormal deposition processes occurring along theproduction line. In-line monitoring and control of OLED deposition isimportant for discovery of processing issues, yield control, and cost ofproduction during batch processing such that issues are discovered priorto a number, e.g., 1 panel, 3 panels, etc., are processed using thesuboptimal deposition processes. In other words, discovering problems innear real-time before a significant portion or all of a run of wafersare processed through the deposition system. In addition, opticalimaging and/or ellipsometry methods if adopted in line can be sensitiveto the vibration of the multiple deposition chambers of the OLEDdeposition system, making it difficult to extract process informationrelated to dopant concentrations and layer thicknesses.

The technology of this patent application utilizes an in-line processmonitoring and control system for providing in-line feedback to alight-emitting diode production line, e.g., an organic light-emittingdiode (OLED) production line. For example, measurements can be performedbetween the multiple deposition or overall fabrication processes in themultiple chambers in the production line.

More particularly, the technology utilizes an in-line metrology headlocated within a transfer chamber between two or more depositionchambers of an OLED production line. The metrology head can include anarray of metrology devices and that are positionable with respect to aworkpiece including one or more deposited layers that are beingmeasured, such that a particular region of the workpiece can be measuredusing the array of metrology devices of the metrology head. Metrologydevices can provide feedback regarding deposition rates via measuredfilm thicknesses for the two or more deposition chambers and dopingconcentrations for the respective films deposited. Metrology devices formeasuring film thickness can be reflectometry and/or transmissioncharacterization devices (e.g., light source, optical components,spectrometer, etc.) or digital holographic microscopy devices (DHM). Thedetermined film thicknesses can be used in combination withphotoluminescence measurements performed on the respective films byphotoluminescence characterization devices (e.g., light source, opticalcomponents, a spectrometer, etc.) to extract doping concentrationinformation for the deposited films. The metrology head located withinthe transfer chamber can include portion or all of the hardwarenecessary for performing the transmission/reflection, DHM, and/orphotoluminescence measurements. Alternatively, a portion of the in-lineprocess monitoring and control system can be located outside of thetransfer chamber, e.g., out of vacuum, such that the metrology headin-vacuum is configured to provide a signal (e.g., data collected from asensor, electromagnetic waves collected from the sample surface, etc.)to the in-line process monitoring and control system located outside ofvacuum (e.g., a spectrometer, sensors, interferometers, additionalcameras, data processing apparatus, etc.).

Measurements can be made on the one or more deposited layers on theworkpiece using test regions located on the workpiece, where each testregion can be a single layer of deposition by a particular depositionchamber of the OLED production line. Each test region can be selectivelyexposed to deposition of material in the particular deposition chamberusing a mask deposition process, e.g., where the test region isselectively exposed to deposition of material in the particulardeposition chamber.

In-Line Process Monitoring and Control System

FIG. 1 illustrates a schematic of an example organic light-emittingdiode (OLED) deposition system 100 including an in-line processmonitoring and control system 102. The OLED deposition system 100 caninclude one or more vacuum chambers connected together, e.g., usingvacuum-isolation gate valves. In general, the OLED deposition system 100is arranged as a closed processing line. The workpieces 106 are loadedinto the deposition system 100 at a beginning of the line. Theworkpieces 106 are moved through and processed sequentially in multipleprocess chambers without being removed from the deposition system 100and while being maintained in the controlled, e.g., vacuum, environmentof the deposition system 100. Finally, the workpieces are unloaded fromthe deposition system 100 at the end-of-line. One or more load-lockchambers 101 can be connected to the OLED deposition system 100, e.g.,at the beginning and end of the line, and can be used to separate theinterior of the OLED deposition system 100 from the external environmentwhile permitting the workpiece 106, to be loaded into/removed from thesystem 100. Vacuum conditions within the system 100 can be maintained byone or more vacuum pumps 103 in fluidic contact with the system 100. Forexample, pressures within the deposition chambers may be maintainedbelow 10E-6 Torr during operation and pressures within transfer chambersand access chambers may be maintained below 10E-4-10E-5 Torr duringoperation of the system 100.

In some implementations, e.g., as shown in FIG. 1, the deposition system100 includes a multiple access chambers 118 arranged in sequence alongthe processing line, with one or more deposition chambers 108, e.g., apair of chambers 108, connected to and accessible through each accesschamber 118. However, many other configurations are possible, e.g., thedeposition chambers themselves could be arranged in an end-to-endsequence with workpieces entering one side of the deposition chamber andexiting another side of the deposition chamber into an access chamber ora different deposition chamber.

The OLED deposition system 100 includes a workpiece transport system104. The workpiece transport system 104 is configured to position aworkpiece 106 within the OLED deposition system 100 under vacuumconditions. The workpiece transport system 104 can be configured to movethe workpiece 106 between multiple deposition chambers 108 whilemaintaining vacuum conditions around the workpiece.

In some implementations, the workpiece transport system 104 includes arail system, e.g., a non-contact magnetic levitation system, and one ormore transfer arms for manipulating the workpiece 106 while maintainingvacuum around the workpiece 106, and where at least a portion of thetransfer arms and rail system are located within the system 100. Forexample, the workpiece transport system 104 can include a rotary robotarm that is movable along the rail 106 and is capable of motion in Z, Rand ⊖.

Alternatively, the workpiece transport system 104 could include multiplerobots, e.g., a robot in each access chamber 118, with each of therobots configured to receive a workpiece 106 from and hand the workpieceoff to another robot in the line or a transfer chamber 110, as well astransfer the workpiece 106 into and out of an adjacent depositionchamber 108.

The workpiece 106 can include various substrates utilized in thefabrication of OLED layer stacks. In some implementations, a workpiece106 is composed of a glass substrate. Other possible substrates include,but are not limited to, plastic, foils, or the like. The workpiece 106can include one or more substrates, e.g., plastic, foils, etc., mountedon a carrier substrate, e.g., glass, silicon, etc., or a chuck, e.g., amolybdenum, ceramic, or stainless steel chuck. The workpiece 106 canvary in dimensions and shape, e.g., rectangular, circular, etc. Eachworkpiece 106 can accommodate multiple OLED layer stacks arranged on asurface of the workpiece 106. During the fabrication of the OLED layerstacks on the workpiece within system 100, multiple test regions can beformed to provide deposition process feedback to the system 100. Furtherdiscussion of the test regions is found below, for example, withreference to FIG. 4.

The OLED deposition system 100 includes multiple deposition chambers108. Each deposition chamber 108 is configured to deposit a respectivelayer of organic material from the OLED layer stack that provides theOLED device onto the workpiece 106. For example, different chambers canbe used to deposit different ones of an electron injection layer (EIL),an electron transport layer (ETL), a hole blocking layer (HBL), thelight emissive layer (EML), an electron blocking layer (EBL), a holetransport layer (HTL), and a hole injection layer (HIL). The organicmaterial in each of the multiple deposition chambers 108 can be selectedto form an OLED or other organic-based light emitting or absorbingdevice. Each deposition chamber can be configured to include respectivepumps, controllers, and monitoring devices to operate and monitor therespective deposition chamber 108. Multiple deposition chambers 108 canbe used to deposit the same layer from the stack, e.g., to provideparallel processing of multiple workpieces and thus increase systemthroughput.

The multiple deposition chambers 108, e.g., 15 to 30 deposition chambers108, can be arranged with respect to the system 100 such that eachsequential layer to form the OLED is deposited by an adjacent depositionchamber 108.

In some implementations, one or more isolation valves and/or gate valvescan be utilized to isolate each deposition chamber 108 from each otherdeposition chamber 108 and the system 100 at a given point in time,e.g., during a deposition process. In particular, one or more isolationvalves and/or gate valves can be utilized to isolate each depositionchamber 108 from the adjacent access chamber 118.

Each of the multiple deposition chambers 108 is coupled together suchthat vacuum is maintained around the workpiece 106 while the workpieceis transferred between a first deposition chamber 108 a and a seconddeposition chamber 108 b of the two or more deposition chambers by theworkpiece transport system 104.

The system 100 further includes one or more transfer chambers 110interconnected to the two or more deposition chambers 108 and configuredto receive the workpiece 106 from the two or more deposition chambers108 by the workpiece transport system 104 while maintaining vacuum andretaining the workpiece 106 within the transfer chamber 110. As depictedin FIG. 1, transfer chamber 110 a serves as the workpiece transfer pointbetween deposition chambers 108 c, 108 d, and deposition chamber 108 e,108 f, where a workpiece 106 can be transferred to the transfer chamber110 a from deposition chambers 108 c-f, e.g., using the workpiecetransfer system 104. In particular, the transfer chamber 110 a can belocated between access chambers 118 a and 118 b; workpieces aretransferred from deposition chambers 108 a or 108 b, through the accesschamber 118 a into the transfer chamber 110 a, and then from thetransfer chamber 110 a through the access chamber 118 b to depositionchambers 108 c or 108 d.

In some implementations, the transfer chamber 110 can be isolated fromthe two or more deposition chambers 108 using one or more isolationvalves and/or gate valves. The transfer chamber 110 can include arespective vacuum pump 103 and vacuum monitoring devices, e.g., a vacuumgauge and controller, to monitor a vacuum level within the transferchamber 110. At least a portion of the in-line processing and controlsystem 102 can be located within the transfer chamber 110, as depictedin FIG. 1.

In-line processing and control system 102 is configured to perform oneor more measurements on the workpiece 106 while the workpiece 106 islocated within the transfer chamber 110 and under vacuum conditions.Furthermore, the one or more measurements performed by the in-lineprocessing and control system 102 can occur between deposition processesof the respective deposition chambers 108 during a sequence ofdepositions on the workpiece 106 to form a OLED layer stack. Forexample, in-line processing and control system 102 is configured toperform one or more measurements on a workpiece 106 after respectivedeposition processes, e.g., respective depositions of layers of organicmaterials, are performed by deposition chambers 108 a-d and prior to adeposition by deposition chamber 108 e. In another example, in-lineprocessing and control system 102 is configured to perform one or moremeasurements on a workpiece 106 after a deposition process, e.g., adeposition of an organic layer on the workpiece, by deposition chamber108 f and prior to a deposition process on the workpiece 106 bydeposition chamber 108 g.

In some implementations, in-line processing and control system 102 isconfigured to perform the one or more measurements on the workpiece inmultiple transfer chambers 110, e.g., chamber 110 a and 110 b. At leasta portion of the in-line processing and control system 102 can belocated within the transfer chamber 110 and under vacuum conditions andcan be in data communication with one or more data processingapparatuses and/or controllers located outside of vacuum.

In some implementations, additional optics and measurement devices maybe located outside of vacuum and can receive a signal from a metrologyhead 112 located within the transfer chamber 110, e.g., within vacuum.The signal from within the transfer chamber 110 can be transmitted tothe in-line processing and control system 102, e.g., wirelessly orthrough a communication line that extends through a port in a wall ofthe transfer chamber 110. In some implementations, the metrology head112 is located outside the transfer chamber, 110, and has a view of theworkpiece using a viewport located on the transfer chamber 110 wall. Insome implementations, a sensor of the metrology head 112 is locatedoutside the transfer chamber 110, and light reflected or transmittedfrom the workpiece passes through a fiber optic connect using a vacuumfeedthrough to the sensor.

The in-line processing and control system 102 can receive measurementdata from at least one metrology head 112. The in-line processing andcontrol system 102 can receive measurement data from multiple metrologyheads 112 located at respective multiple transfer chambers 110 and/ormultiple in-line processing and control system 102 can each collectmeasurement data, e.g., using a data processing apparatus 114 in datacommunication with the one or more metrology heads 112, from respectivemetrology heads 112.

The one or more metrology heads 112 can each include multiplecharacterization devices, e.g., an array of characterization devices,and are at least partially located within a transfer chamber 110.Further details of the configuration of the metrology head 112 arediscussed with reference to FIGS. 3A and 3B below.

The metrology head 112 is positionable with respect to the workpiece 106that is retained within the transfer chamber 110. For example, themetrology head 112 can be mounted within the transfer chamber 110 tohave multiple degrees of freedom, e.g., tip/tilt or linear actuation,with respect to a surface of the workpiece 106. Metrology head 112 caninclude sensors to assist with alignment of the metrology head 112 withrespect to the surface of the workpiece 106, e.g., to set a particulardistance between an objective lens of the metrology head 112 and thesurface of the workpiece 106.

Each metrology head 112 is configured to perform multiple measurementson the workpiece 106 while the workpiece is located within the transferchamber 110. Further details of the different measurements performed bythe metrology head 112 are discussed below with reference to FIGS. 2Aand 2B.

In some implementations, the metrology head 112 or transfer chamber 110can include a vibration sensor to measure a level of vibration of theworkpiece 106 and metrology head 112 during a measurement of theworkpiece 106. The measurements on the workpiece 106 can be performedwithin a frequency range that is faster than the vibration-induceddisplacement of the workpiece by the operation of the system 100.Additionally, averaging processes, normalization, or similarpost-processing methods can be applied to the measurements to accountfor the vibration of the workpiece 106 and metrology head 112 during themeasurements of the workpiece 106.

The system 100 further includes a controller 116 operable to control asequential deposition of the respective layers of organic material ontothe workpiece 106 by the multiple deposition chambers 108, e.g., two ormore deposition chambers 108, to form an organic light-emitting diodelayer stack. The controller 116 can be in data communication andoperable to coordinate the location of the workpiece 106 using theworkpiece transfer system 104 within the system 100 such that theworkpiece 106 is sequentially moved to each respective depositionchamber 108 in turn.

Additionally, the controller 116 can be configured to receive processfeedback data from the in-line processing and control system 102, wherethe process feedback data received can be utilized by the controller 116to determine one or more changes to the operation of the system 100 forthe fabrication of an OLED layer stack. Further details of the processfeedback is discussed below with reference to FIGS. 2A, 2B, and 7.

In some implementations, the metrology head 112 is configured to performone or more measurements on the workpiece 106 within the transferchamber 110. FIG. 2A illustrates a schematic of an example transferchamber 200, e.g., transfer chamber 110, including an in-line processmonitoring and control system 102 that is configured to performmeasurements on the workpiece 106.

The in-line process monitoring and control system 102 can include anin-vacuum metrology head 202, e.g., metrology head 112, that is locatedwithin the transfer chamber 200 and positionable within the transferchamber 200 with respect to a workpiece 106 that is located within thetransfer chamber 200. The workpiece 106 can be supported in the transferchamber on a mount 204, e.g., a pedestal, platform, set of lift-pins,springs, etc. In some embodiments, the workpiece can be chucked to themount 204, e.g., the mount can be an electrostatic chuck.

In some implementations, the in-vacuum metrology head 202 includesoptical components to couple light from in-vacuum components 202 a, 202b through free-space to the workpiece 106 on the mount 204. Thein-vacuum metrology head 202 can include one or more fiber opticscoupled from an out-of-vacuum component 210 into the transfer chamber200 via a vacuum feedthrough.

In some implementations, the in-vacuum metrology head 202 can includeone or more in-vacuum components, e.g., a first in-vacuum component 202a for performing photoluminescence (PL) measurements on the workpiece106 located in the transfer chamber 200 and a second in-vacuum component202 b for performing reflectometry measurements on the workpiece 106located in the transfer chamber 200. Each of the in-vacuum components202 a, 202 b of the in-vacuum metrology head 202 can be separatelypositionable with respect to the workpiece, e.g., to account for aparticular focal distance of the particular in-vacuum component 202 a,202 b or for different test pieces locations. Each in-vacuum component202 a, 202 b of the in-vacuum metrology head 202 can provide respectivelight signal 206 incident to a surface 207 of the workpiece 106 andcollect a reflected signal 208 from the surface 207 of the workpiece106, e.g., using collection optics and/or a detector located in themetrology head 202. Further details of the configuration of the opticalcomponents for performing reflectance and PL measurements are describedbelow with reference to FIG. 5.

In some implementations, the in-vacuum metrology head 202 can include afirst in-vacuum component 202 a for performing interferometricmeasurements on the workpiece 106 in the transfer chamber 200 and asecond in-vacuum component 202 b for performing photoluminescence (PL)measurements on the workpiece 106 in the transfer chamber 200. Theinterferometric measurements may be performed as part of a digitalholographic microscopy (DHM) process. Further details of theconfiguration of the optical components for performing PL and DHMmeasurements is described below with reference to FIG. 6.

Each in-vacuum component 202 a, 202 b of the in-vacuum metrology head202 can provide an output signal 208 a to an out-of-vacuum metrologycomponent 210, where each output signal 208 a can be a differentwavelength range, different intensity, etc. The out-of-vacuum metrologycomponent 210 can include one or more out-of-vacuum components, e.g.,out-of-vacuum components 210 a, 210 b, that correspond to respectivein-vacuum components 202 a, 202 b. For example, a first out-of-vacuumcomponent 210 a can include a PL measurement apparatus that is locatedout-of-vacuum and that corresponds to an in-vacuum component 202 a ofthe in-vacuum metrology head 202 for performing PL measurements,including a spectrometer, a light modulation source, and the like.

The operations of the in-vacuum metrology head 202 and out-of-vacuummetrology component 210 of the in-line processing and control system 102can be controlled by a metrology control unit (MCU) 212 that is in datacommunication with the respective in-vacuum metrology head 202 andout-of-vacuum metrology component 210. In some implementations, each ofthe respective in-vacuum components 202 a, 202 b and out-of-vacuumcomponents 210 a, 210 b is in data communication with an MCU 212 and/orcan each have a respective MCU 212 that is configured to performmeasurements and receive data from the respective metrology component.

In some implementations, an MCU 212 can control the operations ofmultiple different metrology components located in respective transferchambers 200, e.g., transfer chambers 110 a and 110 b as depicted inFIG. 1.

The MCU 212 additionally is configured to collect measurement data 214from the out-of-vacuum metrology component 210, where the measurementdata 214 includes, for example, PL data, reflectance data, DHM-generateddata, transmission data, and the like. The measurement data 214 providedto the MCU 212 can be analyzed to obtain measured values 216 for one ormore deposition characteristics of the deposited layers on the workpiece106. The measured values 216 can in turn be utilized to adjust processparameters of the deposition chambers 108 of the system 100 forsubsequent workpieces, i.e., a feedback process. The depositioncharacteristics can include intrinsic and extrinsic characteristics, forexample, doping concentration of one or more deposited layers, layerthicknesses of the one or more deposited layers, surface morphology(e.g., surface roughness) of the one or more deposited layers, and thelike. Extraction of the values for the deposition characteristics by theMCU 212 is discussed below in further detail with reference to FIGS. 5and 6.

The values 216 for the deposition characteristics are provided to amanufacturing execution system (MES) 220. The MES 220 can receivedmeasurement data 214 and/or values 216 for deposition characteristicsfrom multiple MCU 212 for a particular transfer chamber 200 or frommultiple transfer chambers 220. The MES 220 can compare the measuredvalues 216 for the deposition characteristics to a set of desired values218 for the deposition characteristics, e.g., desired doping ranges forrespective layers, desired layer thicknesses, and the like, and generateone or more adjusted values 222 for the process parameters to compensatefor deviations of the deposition characteristics from the desiredvalues. The adjusted process parameters 222 can be provided to one ormore of the deposition chambers 108 of the system 100.

In some implementations, the deposition characteristics include dopantconcentration and layer thickness for a particular deposited layer. Thevalues 216 for the deposition characteristics are provided to themanufacturing system in a closed-loop feedback system to be used inadjusting fabrication parameters of the manufacturing/depositionprocess. Algorithms can be employed to receive normalized dopingconcentration as input and provide, as output, one or more fabricationparameters to one or more deposition chambers 108, e.g., depending onthe number of films measured during the characterization step.

In some implementations, the MES 220 can be configured to determine,from the values 216 for the deposition characteristics, updatedprocessing information for one or more of the deposition chambers 108and provide, to the one or more of the deposition chambers 108, updatedprocessing information. The values 216 for the depositioncharacteristics can include deposition rate data for the particulardeposition chamber 108 and doping concentration data for a particulardeposition chamber 108 of the multiple deposition chambers.

In some implementations, measurements on the workpiece 106 within thetransfer chamber includes a thickness measurement of a layer depositedin a particular deposition chamber and a doping concentration of thegiven layer of a plurality of layers deposited by the particulardeposition chamber 108 of the two or more deposition chambers.

In some implementations, secondary processing control data can beprovided to the IVIES 220 by one or more second processing control dataunits 221. Secondary processing control data can be, for example, deviceperformance data correlating to thicknesses of deposited layers anddopant level measurements. Device performance data can include, forexample, color coordinate data and luminescence data collected from OLEDdevices. The device performance data can be combined with the thicknessand dopant level measurements performed using system 100 to determinethe proper process adjustments.

In some implementations, the in-vacuum metrology head of the in-lineprocessing and control system 102 is configured to performtransmission-based measurements on the workpiece 106 within the transferchamber 110. FIG. 2B illustrates a schematic of another example transferchamber 250 including an in-line process monitoring and control system102.

As depicted in FIG. 2B, the in-line processing and control system 102includes an in-vacuum component 254, e.g., a detector, that is locatedopposite of the surface 207 of the workpiece 106. In someimplementations, the detector 254 can be affixed to the in-vacuumworkpiece mount 204 such that a light signal that is transmitted throughthe workpiece can be collected by the detector 254.

In some implementations, in-vacuum component 254 includes collectionoptics and a spectrometer located opposite of the surface 207 of theworkpiece 106 to perform transmission measurements. In the exampledepicted in FIG. 2B, transmission measurements are performed on aworkpiece 106 where the workpiece does not have any metallization orother back contact layer to prevent transmitted light from one or moredeposited layers from reaching the detector 254. Collected light signal208 from the detector 254 can be provided back to the out-of-vacuummetrology component 210, e.g., as electrical signals.

In some implementations, the metrology head 112 is configured to performa combination of transmission-based and reflectance-based measurementson the workpiece 106, including multiple in-vacuum metrology heads,e.g., in-vacuum components 202 a, 202 b and 254, positioned with respectto the workpiece to capture reflectance and transmission data,respectively.

In some implementations, the in-vacuum metrology head 202, 252 caninclude multiple metrology devices, e.g., light sources, detectors,collection optics, or the like, where the multiple metrology devices canbe arranged in an array that is positionable with respect to a workpiece106 in the transfer chamber 112. FIGS. 3A-3C illustrate schematics of ametrology device array 300. As depicted in FIG. 3A, a metrology devicearray 300 can include multiple metrology devices 302 aligned withrespect to axis A-A. Referring now to FIG. 3B, which depicts across-section of the metrology device array 300 along axis A-A, themetrology device array 300 can be positioned with respect to a workpiece304, e.g., workpiece 106.

In some implementations, the metrology device array 300 can bepositioned with respect to a surface 305 of the workpiece 304, such thateach metrology device 302 can independently measure a respective testregion 306 located on the workpiece 304 to procure measurement resultsfrom multiple test regions simultaneously. A further discussion of testregions and layout on the workpiece is provided below with reference toFIG. 4.

In some implementations, as depicted in FIG. 3A, the metrology devicearray 300 can consist of multiple metrology devices 302 arranged in alinear configuration along a particular axis, e.g., the X-axis. A linearactuator can scan the metrology device array 300 linearly across theworkpiece in a direction perpendicular to the X-axis so as to collectmeasurements from across the entire workpiece.

FIG. 3C depicts a two-dimensional array of metrology devices 302, wherethe metrology device array 320 includes a panel of metrology devicesarranged along multiple axis. This array of metrology devices 302 canremain stationary while collecting measurements from across the entireworkpiece.

FIG. 4 illustrates a schematic of an example workpiece including testregions. Workpiece 400, e.g., workpiece 106, includes multiple testregions 402 deposited on the workpiece 400 by respective depositionchambers 108 of the system 100 as well as at least one device region406. The device region 406 includes multiple layers deposited on theworkpiece 400, e.g., two or more of an electron layer (EIL), an electrontransport layer (ETL), a hole blocking layer (HBL), a light emissivelayer (EML), an electron blocking layer (EBL), a hole transport layer(HTL) and a hole injection layer (HIL), to form one or more OLED deviceswithin the device region 406. Each test region 402 can providedeposition information related to the performance of a particulardeposition chamber 108. Device region 406 may additionally include testregions 402, where information about the multiple deposited layers onthe workpiece 400 can be extracted from measurements performed on thedevice region 406.

In some implementations, the multiple layers deposited on the workpiece400 are each deposited in sequence by a respective deposition chamber ofthe multiple deposition chambers, e.g., multiple deposition chambers 108of system 100. Each deposited layer of the multiple deposited layers onthe workpiece 400 is deposited by a respective deposition chamber 108through a mask, e.g., a hard mask or a resist mask. The masks can haveidentical patterns for the device region 406, so that each layer isdeposited in an overlapping manner on the same device region 406. On theother hand, the different masks for the different layers have aperturesat different locations defining the different test regions 402. In otherwords, the test region 402 for a particular deposited layer is at aunique location on the workpiece 400, such that each deposited layer ofthe multiple layers deposited on the workpiece 400 has a different testregion 402.

In some implementations, characterization measurements can be performedon pre-designated process measurement features, e.g., thickness squares,fiducial features, or on single deposited layers. As depicted in FIG. 4,test regions 402 can be utilized for characterization measurements ofparticular layers, where each test region may correspond to a particulardeposited layer from a respective deposition chamber 108, e.g., eachtest region is a single layer thick and composed of a deposited layer ofa particular organic material.

Each test region 402 includes a subset, i.e., less than all of, thedeposited layers from the device region 406. In some implementations,each of some or all of the test regions 402 includes exactly one of thedeposited layers from the device region 406. In some implementations,each of some or all of the test regions 402 include a deposited layercorresponding to exactly one of the multiple deposition chambers 108. Byscanning multiple test regions 402 on the workpiece 400 using themetrology head 112, e.g., metrology device array 300, the in-lineprocess and control system 102 can perform a set of characterizationmeasurements on the multiple test regions 402 and extract depositioninformation for each of the multiple deposition chambers 108.

Because each test region 402 includes only a single layer depositeddirectly onto the underlying workpiece 400, a relatively simple opticalmodel can be used, thus reducing computing load. In addition,uncertainly in the thickness measurements due to variations inunderlying layers is reduced or eliminated.

In some implementations, each test region 402 can include multiplelayers deposited onto the workpiece 400, where depositioncharacteristics may be extracted from measurements made on the multipledeposited layers of a particular test region 402 using deconvolutiontechniques. Sequential measurements of each layer of the multipledeposited layers can be performed prior to the deposition of thesubsequent layers in order to extract deposition characteristics for themultiple layer stack.

In some implementations, a test region can be an alignment hash 404,where the alignment hash 404 can serve both as a test region fordeposition characterization as well as alignment marks for aligning themetrology head 112 and/or aligning the workpiece 400 within a depositionchamber 108 during a deposition process.

As described above with reference to FIGS. 2A and 2B, the in-lineprocess and control system can perform multiple differentcharacterization measurements on the workpiece within the transferchamber to extract deposition characteristics related to the depositionprocesses for the multiple deposition chambers 108. Referring now toFIG. 5, in some embodiments, the characterization measurements performedon the workpiece 108 include reflectometry and photoluminescencemeasurements. FIG. 5 illustrates a schematic of an example reflectometryand photoluminescence apparatus for an in-line process monitoring andcontrol system.

As depicted in FIG. 5, a workpiece 502, e.g., workpiece 106, is locatedwithin the transfer chamber 500, e.g., on a mount 204. An in-vacuummetrology head 504, e.g., in-vacuum metrology head 202, can be locatedwithin the transfer chamber 500 and is configured to be positionablewith respect to the workpiece 502. A height/tilt sensor 506 located onthe in-vacuum metrology head 504 can determine a position and/or tilt ofthe workpiece 502 with respect to the head 504. The head 504 can bepositioned to maintain a constant height and tilt with respect to asurface 503 of the workpiece 502. The support 204 and/or the head 504can be coupled to one or more actuators that provide relative motion soas to achieve the desired relative height and tilt.

The in-vacuum metrology head 504 can further be configured to direct,e.g., via a set of optical components, one or more light beams 508 to asurface 503 of the workpiece 502. In some implementations, the one ormore light beams 508 can be directed to the surface 503 of the workpieceusing one or more of free space optics and/or fiber optics. The multiplelight beams 508 can each have respective different values for one ormore optical characteristics including, for example, wavelength ranges,light intensities, pulse shape, and the like.

As depicted in FIG. 5, multiple out-of-vacuum metrology components 510a, 510 b can be in data communication with the in-vacuum metrology head504. Out-of-vacuum metrology component 510 a includes multiple metrologycomponents 512 for performing reflectometry measurements on theworkpiece 502, including collection optics and spectrometer 512 b and alight source 512 a, e.g., a xenon, mercury, or halide high energy lightsource. For example, a Xe lamp with a power output of 30-500 W or highercan be used. In some implementations, one or more fiber optics can beutilized in combination with vacuum feedthroughs to transmit lightcollected by collection optics located in-vacuum to the out-of-vacuummetrology components 510 a, 510 b.

The light source 512 a provides a light beam 508 with which to probe thesurface 503 of the workpiece 502, and the spectrometer 512 b isconfigured to collect and process the reflected light signal 514 fromworkpiece 502.

Out-of-vacuum metrology component 510 b includes multiple metrologycomponents 516 for performing photoluminescence (PL) measurements on theworkpiece 502 in the transfer chamber 500, including a light source 516a, power meter 516 b, and beam-splitter 518. Light source 516 a can be,for example, an ultraviolet (UV) laser, lamp, or LED. For example, a 405nm UV laser with an average power output of a few μW to a few mW can beused. Power output of the light source 516 a can be selected to be lowerthan photo-bleaching effect regimes, e.g., where photoluminescenceintensity output will be time-dependent on exposure to the light source516 a. Power meter 516 b can be utilized to sample the beam energy andcan include, for example, a photodiode sensor. Beam-splitter 518 can beutilized to divide the beam of the light source 516 a in order to samplea reference beam.

Whereas the light beam 508 a from the light source 512 a can be directedonto the workpiece 502 along an axis normal to the surface of theworkpiece 502, the light beam 508 b from the light source 516 a can bedirected onto the workpiece 502 along an axis at an oblique anglerelative to the surface of the workpiece 502.

In some implementations, an out-of-vacuum metrology component 510 caninclude a light modulation unit configured to provide two differentlight sources 508 to the in-vacuum metrology head 504, e.g., havingdifferent amplitudes, phase, polarization, or the like.

In some implementations, a thickness of the deposited layer on theworkpiece 502 is measured using the in-vacuum metrology head 504 andout-of-vacuum metrology component 510 a by collecting a modulated sourcesignal 508 and the reflected signal 514 by the spectrometer 512 a. Thecollected data can be analyzed to determine a thickness of the depositedlayer. For example, a controller can store a library of referencespectra, each reference spectrum having an associated thickness value. Ameasured spectrum can be compared to the library of reference spectra,and the reference spectrum that is the best fit to the measuredspectrum, e.g., using a sum of squared differences metric, can beselected as a matching reference spectrum. The thickness value that isassociated with the matching best-fitting reference spectrum can then beused as the measured thickness value.

In some implementations, a photoluminescence (PL) measurement isperformed using the in-vacuum metrology head 504 and out-of-vacuummetrology component 510 b. The PL measurement can be utilized, incombination with the reflectometry measurement described above, tocalculate a dopant level in a particular deposited layer. Calculatingdopant levels, which are an extrinsic factor, includes determining anormalization factor to convert the data to an intrinsic, materialsproperty factor. The extrinsic factors to consider include: (1)thickness for total materials in the analysis volume, e.g., thedeposited layer(s) of interest on the workpiece, (2) laser intensity oflight source 516 a, and (3) working distance change and tilt angle whichaffects the analysis volume. As such, ideal analysis system will measurethe thickness, which is done by the reflectometry apparatus usingout-of-vacuum metrology head 510 a and in-vacuum metrology head 504.Laser intensity (excitation source for PL) can be determined by (1) useof a power meter 516 b and (2) beam splitter 518 to portion going to theworkpiece 502 and the power meter 516 b, and (3) calibration factorbetween the reading on power meter and workpiece. Working distancechange and tilt angle can be corrected by measurement sensors 506 and aposition of the in-vacuum metrology head 504 with respect to a surface503 of the workpiece 502.

In some implementations, beam-splitter 518 is utilized to split aportion of the light beam 508 b from light source 516 a and direct ittowards the power meter 516 b to be measured. A photoluminescence signal509 from the deposited layer on the workpiece 502 is collected at thespectrometer, e.g., spectrometer 512 a or another spectrometer locatedin out-of-vacuum metrology component 510 b (not pictured). The measuredPL data is analyzed, e.g., by plotting the signal intensity versuswavelength and a Gaussian curve is fit to the plot. The maximumwavelength, maximum intensity and full-width at half-maximum (FWHM) arefound and normalized to the intensity of the light beam 508 b from lightsource 516 a and the thickness of the deposited layer as determinedusing the reflectometry measurements. The normalized plot is compared toone or more calibration plots or “golden samples” (as described infurther detail with reference to FIG. 7 below), and a dopant level inthe deposited layer is determined.

In some implementations, the thickness and dopant level data extractedusing the PL and reflectometry measurements are sent to the MES 220 fordetermining process factor adjustments and providing the adjustedprocess factor(s) to one or more deposition chambers 108. Furtherdetails are described with reference to FIG. 7 below.

In some implementations, a process factor adjustment for adjusting athickness of the deposited layer includes modulating the staticdeposition rate, e.g., an evaporation temperature, a scanning rate,e.g., a dynamic deposition rate, or both to achieve the desiredthickness. A process factor adjustment to achieve a desired dopant levelcan include adjusting relative deposition rates, e.g., evaporationtemperatures and scanning rate. Such a shift deposition rates has impacton total thickness. As such, the two adjustments would need to becorrelated to ensure both the thickness and dopant level specificationsare met.

FIG. 6 illustrates a schematic of an example digital holographicmicroscopy (DHM) device and photoluminescence (PL) apparatus for anin-line process monitoring and control system. As depicted in FIG. 6, aworkpiece 602, e.g., workpiece 106, is located within the transferchamber 600, e.g., on a mount 204. An in-vacuum metrology head 604,e.g., in-vacuum metrology head 202, including or more in-vacuumcomponents, can be located within the transfer chamber 600 and isconfigured to be positionable with respect to the workpiece 602,similarly as described with reference to in-vacuum metrology head 504with reference to FIG. 5.

Additionally, some or all of the components of a DHM device 612 a can belocated inside the transfer chamber 600, where a reference beam and asample beam from light source 613 can be provided into the transferchamber 600 via fiber optics. The DHM device 612 a includes thenecessary components required to perform interferometric measurementsaccording to known standard. Components of the DHM device 612 a includea light source 613, optics forming a Michelson interferometer, e.g.,dichroic mirrors 622 and mirrors 621, and a detector 615, e.g., a CCDcamera.

Briefly, the interferometric measurement can be performed by splitting abeam from light source 613 using a beam splitter 622 a into a referencelight beam 608 b as a reference wave front and an object light beam 608a. The object light beam 608 a is provided to the workpiece 602 toilluminate a test region of the workpiece 602, e.g. test region 402,creating an object wave front. The reflected object wave front iscollected by a microscope objective 620 and the object and referencewave fronts are joined together by a second beam splitter 622 b tointerfere and create a holographic image which is recorded by a CCDcamera 615. Other possible configurations are possible with the end goalto produce an interferometric interference pattern at the CCD 615 andgenerate a digitally constructed image. The reflected object wave frontcan additionally be split off using a third beam splitter 622 c andcollected by a spectrometer 619.

The height/tilt sensor 606 located on the in-vacuum metrology head 604can collect depth-of-focus information, tilt information, spatial depthinformation and can determine a position and/or tilt of the workpiece602 with respect to the microscope objective 620 and/or head 604, wherethe microscope objective 620 and/or head 604 can be positioned tomaintain a constant height and tilt with respect to a surface 603 of theworkpiece 602. The DHM device 612 a and/or head 604 can be coupled toone or more actuators that provide relative motion so as to achieve thedesired relative height and tilt.

The in-vacuum metrology head 604 can further be configured to direct,e.g., via a set of optical components, one or more light beams, e.g.,from out-of-vacuum metrology head 510 b to a surface 603 of theworkpiece 602. In some implementations, the one or more light beams canbe directed to the surface 603 of the workpiece using one or more offree space optics and/or fiber optics. The multiple light beams can eachhave respective different values for one or more optical characteristicsincluding, for example, wavelength ranges, light intensities, pulseshape, and the like.

As depicted in FIG. 6, one or more out-of-vacuum metrology components610 a, e.g., DHM control unit 617,can be in data communication with theone or more in-vacuum components, e.g., CCD 615.

A DHM control unit 617 can analyze the hologram data captured by the CCD615 and convert it to the 3D topography image. The DHM control unit 617can correct for the focus offset and tilt captured by the height/tiltsensor 606. By correcting for the depth of focus and tilt, the DHMcontrol unit 617 can extract a thickness of the deposited layer on theworkpiece 602.

In some implementations, one or more fiber optics can be utilized incombination with vacuum feedthroughs to transmit light collected bycollection optics location in-vacuum to the out-of-vacuum metrologycomponents 610 a, 510 b.

Similar to the depiction with reference to FIG. 5, out-of-vacuummetrology head 510 b includes multiple metrology components 516 forperforming photoluminescence (PL) measurements on the workpiece 602 inthe transfer chamber 600. Additionally, as described above withreference to FIG. 5, the thickness and dopant level data extracted usingthe PL and interferometric measurements are sent to the MES 220 fordetermining process factor adjustments and providing the adjustedprocess factor(s) to one or more deposition chambers 108. Furtherdetails are described with reference to FIG. 7 below.

Example Process of the In-Line Process Monitoring and Control System

Returning to FIG. 1, in at least some of the transfer chambers, e.g., ineach transfer chamber, the workpiece is measured. In someimplementations, the workpiece passes through each chamber 108 in theline, e.g., through chamber 108 a, chamber 108 b, chamber 108 c, etc. Inthis case, at least for the configuration shown in FIG. 1, the workpiecewould enter a transfer chamber 110 and be measured after having multipleorganic layers deposited—either since the start of the line or since theprior measurement. However, this is not necessary. For example, theworkpiece could pass through only one deposition chamber of each pairthat are accessible from an access chamber 118, e.g., through chamber108 b, chamber 108 d, chamber 108 f, etc. As another example, an accesschamber could have only one deposition chamber. As another example, theaccess chamber could be removed entirely and the deposition chamberscould have direct access to one or more transfer chambers. For example,the workpiece could be moved from a transfer chamber into a depositionchamber through one side of the chamber, and then removed throughanother side of the deposition chamber into another transfer chamber. Inany of these configurations, it is possible for the workpiece to enter atransfer chamber 110 and be measured after having a single organic layerdeposited—either since the start of the line or since the priormeasurement.

In general, the measurements are used to as feedback to control theprocessing parameters of the deposition chamber(s) that deposited thelayer(s) being measured. For example, if a first layer is deposited inchamber 108 a, and the workpiece is then transported to transfer chamber110, the measurements can be used to adjust the processing parameters ofchamber 108 a, e.g., to achieve a target thickness or to improvethickness uniformity. As another example, if a first layer is depositedin chamber 108 a and a second layer is deposited in chamber 108 b, andthe workpiece is then transported to transfer chamber 110, themeasurements can be used to adjust the processing parameters of chambers108 a and 108 b.

FIG. 7 is a flow diagram of an example process of the in-line processmonitoring and control system for the sequential deposition ofrespective layers on a workpiece. In a first step, a first layer of afirst organic material is deposited onto the workpiece within a firstdeposition chamber of the two or more deposition chambers of a system(702). A layer can be deposited by a deposition chamber, e.g.,deposition chamber 108 c, of the multiple deposition chamber 108 ofsystem 100.

The workpiece is transferred, by the workpiece transport system, fromthe first deposition chamber to a transfer chamber, and a first set ofmultiple measurements are performed on the workpiece by the metrologyhead and a data processing apparatus in data communication with themetrology head (704). A workpiece transport system, e.g., workpiecetransport system 104, can transfer the workpiece 106 from the depositionchamber 108 c to a transfer chamber 110 a, where a first set ofmeasurements can be performed on the workpiece 106 by the in-lineprocessing and control system 102, including an in-vacuum metrology head112.

In some implementations, the first set of multiple measurements areprovided to the MCU 212, the output of which is provided to the MES 220,as described in further detail above with reference to FIG. 2A. The MES220 may then in turn determine adjusted process parameters 222 toprovide to the controller 116 of the particular deposition chamber(s)108, e.g., the deposition chamber 108 c, such that a next deposition ona workpiece 106 by the deposition chamber(s) 108 utilizing the adjustedprocess parameters 222.

The workpiece is transferred, by the workpiece transport system, to asecond deposition chamber of the two or more deposition chambers and asecond layer of a second organic material is deposited onto theworkpiece in the second deposition chamber (706). The workpiece 106 canthen be transferred, by the workpiece transport system 104, to a seconddeposition chamber, e.g., deposition chamber 108 e, where a second layeris deposited on the workpiece 106.

In some implementations, the process further includes transferring, bythe workpiece transport system, the workpiece from the second depositionchamber to a third deposition chamber of the two or more depositionchambers and depositing a third layer of a third organic material ontothe workpiece within the third deposition chamber (708). The workpiece106 can be transferred again, by the workpiece transport system 104, toa third chamber, e.g., chamber 108 f via an access chamber 118 b, todeposit a third layer onto the workpiece 106 within the third depositionchamber 108 f.

In some implementations, the process further includes transferring, bythe workpiece transport system, the workpiece from the third depositionchamber to the transfer chamber and performing a second set of multiplemeasurements on the workpiece by the metrology head and the dataprocessing apparatus in data communication with the metrology head(710). The second set of multiple measurements can include informationabout the second deposited layer and third deposited layer that weredeposited on the workpiece. The workpiece 106 can be transferred by theworkpiece transport system 104 from the third chamber 108 f into atransfer chamber 110 b, where a second set of measurements can bemeasured by the in-line processing and control system 102 while theworkpiece 106 is located within transfer chamber 110 b.

In some implementations, the second set of multiple measurements areprovided to the MCU 212, the output of which is provided to the MES 220,as described in further detail above with reference to FIG. 2A. The MES220 may then in turn determine adjusted process parameters 222 toprovide to the controller 116 of the particular deposition chamber(s)108, e.g., the second deposition chamber 108 e and the third depositionchamber 108 f, such that a next deposition on a workpiece 106 by thedeposition chamber(s) 108 utilizing the adjusted process parameters 222.

In some implementations, vibration, e.g., from the moving parts of thesystem 100, is accounted for by averaging the multiple measurementscollected or by otherwise normalizing the collected data.

In some implementations, deposition characteristics include an intrinsicdoping level of a deposited layer. Extracting the intrinsic doping levelof a deposited layer can require information about a deposited layerthickness, e.g., perpendicular to surface 107 of the workpiece, in orderto normalize the intrinsic doping level information. The deposited layerthickness information may be extracted, for example, using reflectometrymeasurements performed on a test region of the particular depositedlayer. In another example, the deposited layer thickness information maybe extracted using interferometric measurements, e.g., using the DHMmeasurement system, performed on the test region of the particulardeposited layer. In yet another example, the deposited layer thicknessinformation may be extracted using transmission measurements performedon the test region of the particular deposited layer.

In some implementations, as depicted in FIGS. 5 and 6, photoluminescencemeasurements can be utilized to extract intrinsic doping of a depositedlayer when normalized to various factors including beam intensity, e.g.,of the laser light source, thickness of the deposited layer, where thethickness is measured using one of the techniques listed above, e.g.,reflectometry, transmission, interferometry, etc, and the tilt and depthof focus of the in-vacuum metrology head with respect to the surface ofthe workpiece, e.g., using tilt/height information from the in-vacuummetrology head.

PL measurements can be calibrated to a set of known intrinsic dopinglevels for various organic materials. In one example, a golden samplecomparison having known thicknesses and dopant levels can be utilized asa calibration sample, e.g., where an absolute intensity of the PLmeasurement of the golden sample is compared to a PL measurement of atest sample. In another example, a calibration chart can be generatedusing a set of samples with known dopant levels for a particular organicmaterial. The calibration chart can include a plot of doping levelversus PL measurement intensity for a particular known thickness of thetest layer, where additional points can be extrapolated along the plot.

In some implementations, a transfer chamber includes a temperaturecontrol and measurement apparatus configured to regulate a temperatureof the workpiece in the transfer chamber in order to performcharacterization measurements of the workpiece at a particulartemperature. Temperature control and measurement apparatus can include atemperature gauge to measure a temperature of the workpiece, e.g., apyrometer, thermocouple contacting a surface of the workpiece, or thelike. Temperature control can be, for example, a cold finger, a Peltiercooler, or the like, to regulate a temperature of the workpiece to aparticular temperature range during a PL measurement of the workpiece.In another example, temperature-dependent characterization measurements,e.g., temperature-dependent PL measurements, can be performed on theworkpiece within the transfer chamber using a temperature control andmeasurement apparatus.

In some implementations, characterization measurements can be performedon two or more deposited layers, where the results of thecharacterization measurements may be de-convoluted from the measurementdata, e.g., transmission data collected through the two or moredeposited layers.

Conclusion

The controller and other computing devices part of systems describedherein can be implemented in digital electronic circuitry, or incomputer software, firmware, or hardware. For example, the controllercan include a processor to execute a computer program as stored in acomputer program product, e.g., in a non-transitory machine readablestorage medium. Such a computer program (also known as a program,software, software application, or code) can be written in any form ofprogramming language, including compiled or interpreted languages, andit can be deployed in any form, including as a standalone program or asa module, component, subroutine, or other unit suitable for use in acomputing environment.

While this document contains many specific implementation details, theseshould not be construed as limitations on the scope of any inventions orof what may be claimed, but rather as descriptions of features specificto particular embodiments of particular inventions. Certain featuresthat are described in this document in the context of separateembodiments can also be implemented in combination in a singleembodiment. Conversely, various features that are described in thecontext of a single embodiment can also be implemented in multipleembodiments separately or in any suitable subcombination. Moreover,although features may be described above as acting in certaincombinations and even initially claimed as such, one or more featuresfrom a claimed combination can in some cases be excised from thecombination, and the claimed combination may be directed to asubcombination or variation of a subcombination. A number ofimplementations have been described. Nevertheless, it will be understoodthat various modifications may be made.

1. An organic light-emitting diode (OLED) deposition system comprising:a workpiece transport system configured to position a workpiece withinthe OLED deposition system under vacuum conditions; two or moredeposition chambers, each deposition chamber configured to depositrespective layers of organic material onto the workpiece, wherein thetwo or more deposition chambers are coupled such that vacuum ismaintained around the workpiece while the workpiece is transferredbetween a first deposition chamber and a second deposition chamber ofthe two or more deposition chambers by the workpiece transport system; atransfer chamber interconnected to the two or more deposition chambersand configured to receive the workpiece from the two or more depositionchambers by the workpiece transport system while maintaining vacuum andretaining the workpiece within the transfer chamber; a metrology systemhaving one or more sensors positioned to perform measurements of theworkpiece within the transfer chamber; and a control system to control asequential deposition of the respective layers of organic material ontothe workpiece by the two or more deposition chambers to form an organiclight-emitting diode layer stack, the control system configured to causethe first deposition chamber to deposit a first layer of a first organicmaterial onto the workpiece, cause the workpiece transport system totransfer the workpiece from the first deposition chamber to the transferchamber, receive a first plurality of measurements of the workpiece inthe transfer chamber from the metrology system, cause the workpiecetransport system to transfer the workpiece from the transfer chamber tothe second deposition chamber, and cause the second deposition chamberto deposit a second layer of a second organic material onto the firstlayer on workpiece to build at least a portion of the organiclight-emitting diode layer stack.
 2. The deposition system of claim 1,wherein the control system is further configured to determine, from thefirst plurality of measurements, updated processing parameter values forthe first deposition chamber, and cause the first deposition chamber tooperate according to the updated processing parameter values.
 3. Thedeposition system of claim 2, further comprising a second transferchamber and a second metrology system positioned within the secondtransfer chamber, and wherein the control system is configured to causethe workpiece transport system to transfer the workpiece from the seconddeposition chamber to a second transfer chamber, receive a secondplurality of measurements of the workpiece in the second transferchamber from the second metrology system.
 4. The deposition system ofclaim 3, wherein the second deposition chamber is configured to deposita portion of the second layer into a first test region separate from thelight-emitting diode layer stack and that does not overlie the firstlayer, and wherein the second metrology system is configured to performthe second plurality of measurements in the first test region.
 5. Thedeposition system of claim 3, wherein the control system is furtherconfigured to determine, from the second plurality of measurements,updated second processing parameter values for the second depositionchamber, and cause the second deposition chamber to operate according tothe updated second processing parameter values.
 6. The deposition systemof claim 5, further comprising a third deposition chamber of the two ormore deposition chambers, and wherein the control system is furtherconfigured to cause the workpiece transport system to transfer theworkpiece from the second transfer chamber to the third depositionchamber; and cause the third deposition chamber to deposit a third layerof a third organic material onto the second layer on workpiece tocontinue building of the organic light-emitting diode layer stack. 7.The deposition system of claim 1, wherein the metrology system isconfigured to perform photoluminescence measurements on the workpiece inthe transfer chamber.
 8. The deposition system of claim 7, wherein themetrology system is configured to perform a thickness measurement of thefirst layer on the workpiece in the transfer chamber.
 9. The depositionsystem of claim 8, wherein the thickness measurement comprises areflectometry measurement.
 10. The deposition system of claim 8, whereinthe thickness measurement comprises a transmission measurement.
 11. Thedeposition system of claim 8, wherein the control system is configuredto determine a doping concentration of the first layer from thethickness measurement and the photoluminescence measurement.
 12. Thedeposition system of claim 1, wherein the metrology system includes ametrology head movable positioned and movable within the transferchamber.
 13. The deposition system of claim 12, wherein the transferchamber includes a support to receive the workpiece from the workpiecetransport system and hold the workpiece stationary as the metrologysystem takes the first plurality of measurements.
 14. An organiclight-emitting diode (OLED) deposition system comprising: a workpiecetransport system configured to position a workpiece within the OLEDdeposition system under vacuum conditions; two or more depositionchambers, each deposition chamber configured to deposit respectivelayers of organic material onto the workpiece, wherein the two or moredeposition chambers are coupled such that vacuum is maintained aroundthe workpiece while the workpiece is transferred between a firstdeposition chamber and a second deposition chamber of the two or moredeposition chambers by the workpiece transport system; a transferchamber interconnected to the two or more deposition chambers andconfigured to receive the workpiece from the two or more depositionchambers by the workpiece transport system while maintaining vacuum andretaining the workpiece within the transfer chamber; a metrology systemhaving one or more sensors positioned to perform measurements of theworkpiece within the transfer chamber, the metrology system including afirst light source to generate a first light beam, and wherein at leastone of the one or more sensors is positioned to receive reflections ofthe first light beam from the workpiece within the transfer chamber toperform reflectometry measurements and generate a thickness measurementof a layer on the workpiece from the reflectometry measurement, a secondlight source to generate a second light beam to induce photoluminescencein the layer on the workpiece in the transfer chamber, and wherein atleast one of the one or more sensors is positioned to receive emissionsfrom the layer on the workpiece within the transfer chamber to performphotoluminescence measurements of the layer on the workpiece, and acontrol system to control a sequential deposition of the respectivelayers of organic material onto the workpiece by the two or moredeposition chambers to form an organic light-emitting diode layer stack,the control system configured to cause the first deposition chamber todeposit a first layer of a first organic material onto the workpiece,cause the workpiece transport system to transfer the workpiece from thefirst deposition chamber to the transfer chamber, receive the thicknessmeasurement and the photoluminescence measurement from the metrologysystem, cause the workpiece transport system to transfer the workpiecefrom the transfer chamber to a second deposition chamber of the two ormore deposition chambers, and cause the second deposition chamber todeposit a second layer of a second organic material onto the first layeron workpiece to build at least a portion of the organic light-emittingdiode layer stack.
 15. The deposition system of claim 14, wherein thecontrol system is configured to determine a doping concentrationmeasurement of the first layer from the thickness measurement and thephotoluminescence measurement.
 16. The deposition system of claim 15,wherein the control system is further configured to determine, from thedoping concentration measurement, updated processing parameter valuesfor the first deposition chamber, and cause the first deposition chamberto operate according to the updated processing parameter values.
 17. Thedeposition system of claim 14, wherein the metrology system includes ametrology head movable positioned and movable within the transferchamber.
 18. A computer program product comprising a non-transitorycomputer readable medium comprising instructions to cause one or moredata processing apparatuses to: cause a first deposition chamber todeposit a first layer of a first organic material onto a workpiece,cause a workpiece transport system to transfer the workpiece from thefirst deposition chamber to a transfer chamber, receive a firstplurality of measurements of the workpiece in the transfer chamber froma metrology system; cause the workpiece transport system to transfer theworkpiece from the transfer chamber to a second deposition chamber; andcause the second deposition chamber to deposit a second layer of asecond organic material onto the first layer on workpiece to build atleast a portion of an organic light-emitting diode layer stack.
 19. Thecomputer program product of claim 18, wherein the first plurality ofmeasurements include a thickness measurement and a photoluminescencemeasurement, and comprising instructions to determine a dopingconcentration measurement of the first layer from the thicknessmeasurement and the photoluminescence measurement.
 20. The computerprogram product of claim 19, comprising instructions to determine, fromthe doping concentration measurement, updated processing parametervalues for the first deposition chamber, and cause the first depositionchamber to operate according to the updated processing parameter values.